When drilling or locking a screw into an object, an inner hole is usually drilled in the object with an electric drill. The, a screw nut is driven into the hole with a hammer. The screw nut is often fixed inside the hole with a spanner, and thus prevented from loosening. Finally, a screw is threadably attached to the screw nut. In this process, the screw will be firmly locked. As several hand tools will have to be used alternately to achieve these drilling and screw locking operations, not only is time and labor wasted, but this process is not practical. Therefore, such a known process has been gradually replaced by utilizing some other advanced tools.
As shown in FIG. 7, a more advanced tool assembly is presented which comprises a lock cylinder formed by front and rear sections 1 and 2, a drill pillar 3 which can be sleeved within a drill head and the lock cylinder, a steel shot B and a steel shot buckling ring C. By sleeving drill pillar 3 into the lock cylinder, as well as making use of the steel shot buckling ring C, which is set on the surface of the lock cylinder to exert a packing force onto steel shot B to further force it to move into a steel shot groove 31 of drill pillar 3 inside the lock cylinder, drill pillar 3 can be fixed in a desired axial position. However, an axially extending plane 36 is cut on the surface of drill pillar 3 to coordinate with a positioning edge 24 at the rear end of the lock cylinder. When drill pillar 3 is moved forward, a drill head carried by drill pillar 3 can extend out of the lock cylinder for use in a drilling process. A circular arc 38 and a secondary positioning plane 37 are set on the extreme end of plane 36 of drill pillar 3. When drill pillar 3 is being pulled in a counter direction along the lock cylinder such that the drill head will be recessed within the lock cylinder, the lock cylinder will be able to rotate along the circular arc 38. While it moves to secondary positioning plane 37 which corresponds in position to positioning edge 24 of the lock cylinder, drill pillar 3 will not be able to move forward because it is checked by secondary positioning plane 37. This will enable the special pattern 11 at the front end of the lock cylinder to protrude for engagement with a packing screw.
With this construction, the aforesaid conventional structure has been found to be able to achieve the object of rapid drilling and locking by using an ordinary electric drill, to the ultimate effect of shortening the working hours required and saving labor.
After carefully studying the structure of the prior art, however, the inventor found that in the installation of the aforesaid tool assembly which is featured for its rapid changes, drill pillar 3 must first be sleeved into the rear lock cylinder 2. Then, the front lock cylinder is secured to the rear lock cylinder 2 to enable drill pillar 3 to be sleeved into the lock cylinder. After that, steel shot buckling ring C and steel shot B are fixed onto the outer periphery of the lock cylinder. Owing to this complicated assembly procedure the prior art suffers from the following:
a. The complexity of its members makes the assembling process troublesome and time consuming. Moreover, the plurality of parts and the complexity of its structure also increases the cost of its material. Besides increasing its retail price, this cost factor will further result in weakening its market competitiveness. PA1 b. The plurality of members makes its assembling process troublesome and uneasy. The difficulty experienced by ordinary people in understanding its assembling process also causes disturbances. PA1 1. Due to it simple construction and ease of assembly, use of the multi-functional drill and lock assembly reduces processing cross, to the ultimate effect of increasing its production efficiency and capacity.
Furthermore, since plane 26 is cut into drill pillar 3, the average diameter of drill pillar 3 is shortened. Therefore, when drill pillar 3 receives a considerable pressure during use, it will usually break because it cannot sustain the load. In addition, when the secondary positioning plane 37 at the front end of drill pillar 3 is rotated at positioning edge 24 which is located at an extreme end of the lock cylinder, deformation can easily result due to the effect of a powerful torsion being exerted for a long time to the electric drill, as well as the application of stress. When the deformation of plane 37 exceeds the internal diameter of the lock cylinder, it will be impossible for drill pillar 3 to axially slide within the lock cylinder, thus making it impossible to perform its drilling function. Therefore, this conventional technique is considered to be incomplete in its structural design, and further improvement is deemed necessary.